1. Field of the Invention
The present invention relates to a position detection technology for detecting the position of a head on a recording disk medium through a servo area formed on the recording disk medium, and, in particular, relates to a position detection technology for detecting the head position on a recording disk medium from the servo area of an information recording apparatus equipped with a type of positioning mechanism that differs from the positioning mechanism used when the servo area was formed on the medium.
2. Description of the Related Art
An information recording apparatus is a device used for recording and reproducing information.
The information recording apparatus incorporates recording disk media such as a magnetic disk and an optical disk, records information to a specific address on the recording disk medium, and reproduces the information by reading from the specific address.
The address is recorded in advance on the magnetic disk as address information in a magnetic disk device incorporating magnetic disk medium, for example, and information is recorded to or reproduced from a specific address by reproducing the address information via a magnetic head.
In the typical magnetic disk medium, pluralities of tracks with concentric circles are formed from the center of the disk to the circumference. A track has a plurality of sectors, each of which is composed of a servo area and a data area, arranged on the track. In the servo area, position information indicating the position on the magnetic disk medium (a track position and a sector position, etc.) and burst information are formed in a checkered pattern (servo pattern).
The servo pattern is recorded by using a production device called a servo track writer during the production process in a manufacturing facility. The servo track writer comprises a positioning mechanism such as a spindle motor which rotates the magnetic disk medium and a rotary actuator which causes a magnetic head to travel in a radial direction of the disk, and through the use of this positioning mechanism, a mechanism in the finished magnetic disk device is used.
The controller of the servo track writer generates a clock signal accurately synchronized with the rotation of the magnetic disk medium by the spindle motor, sends to the magnetic head a record signal for the servo pattern that differs for each track by synchronizing with the clock signal, and writes the servo pattern on the traveling trajectory of the magnetic head on the magnetic disk medium determined by the positioning mechanism.
The magnetic disk medium in which the servo pattern is written is set to a magnetic disk device as well as the positioning mechanism, and shipped as a product.
Recently, a positioning mechanism that uses a rotary actuator in a magnetic disk device was implemented in many cases for the purpose of size reduction of the device.
However, the rotary actuator has a problem when writing the servo pattern. The effect of this problem is that a magnetization phenomenon occurs such that the servo pattern is erased or unnecessary servo pattern information is recorded in the vicinity of the magnetic head during the writing of the servo pattern as the yawing angle between a tangent line of the track and the magnetic head, which changes in accordance with the radial position of the magnetic head on the magnetic disk medium, increases.
In order to prevent such a phenomenon, there is a method as described in Japanese Patent-Application Publication No. 2004-227735, in which, by the servo track writing from the center of the magnetic disk toward the midpoint and from outer circumference of the magnetic disk medium toward the midpoint, the protruding direction of the magnetic field and the continuation writing direction remain constant so as not to generate undesired servo patterns. In addition to the method, there is an additional effective method, which is a method for writing the servo pattern on the magnetic disk medium by using a positioning mechanism such as a linear actuator, which does not deviate the head trajectory on the recording disk medium and the radial direction of the magnetic disk medium.